Protective headgear is generally worn to shield the wearer from injury-causing blows to the head during athletic contests and recreational activities like football, hockey, bicycling and motorcycling. A conventional protective helmet typically consists of a rigid outer shell lined with at least one layer of resilient material. Such resilient liner material distributes and diminishes the force of impacts delivered to the exterior of the outer shell, and prevents direct transmission of that force to the wearer's head. Thus, a primary objective of protective helmet designs is to maximize the amount of impact energy absorbed and dissipated by the helmet.
In addition to attempting to maximize the absorption and dissipation of impact energy, another objective of protective headgear designs is to achieve a proper fit to the wearer's head. Human skulls are, like fingerprints, all different in shape and size. Consequently, a helmet having fixed internal dimensions cannot provide a comfortable, secure fit for all wearers. In addition, inadequate ventilation or circulation of air through the liner and around the head is a frequent problem in poorly designed helmets.
The present invention takes advantage of certain anatomical commonalities among skulls, and provides for the adjustment of the helmet's internal dimensions to properly fit heads of various shapes and sizes. In particular, the lower rear octants of the skull have been found to provide an effective location for securing the helmet to the head to maintain proper positioning during use. The lower rear octants of the skull are the portions of the skull opposite the face and immediately above the base of the skull. In addition, the crown or topmost region of the skull, as well as the upper octants of the skull generally, including the temples, have been found to provide an effective platform upon which to elevate the helmet from the head.
The present invention employs a bladder having cells that extend over the crown or upper front octants and over the lower rear octants of the head. Upon inflation through a single valve, the bladder cells apply pressure to these locations to properly and comfortably position the outer shell and resilient liner around the wearer's head.
Adjustable helmets in the past have mostly failed to take advantage of the anatomical characteristics of the skull utilized by the present invention. For example, Schneider U.S. Pat. No. 3,462,763 describes an inflatable helmet pad which extends over the crown, front, sides and rear of the wearer's head. The inflatable pad of the Schneider patent, however, does not extend over the lower rear skull octants, and therefore would not be as effective in properly securing the helmet to heads of different shapes and sizes. Similarly, Conroy U.S. Pat. No. 3,688,704 describes an inflatable helmet pad formed of a single cell extending over the top, front and sides of the head, but the cell does not extend to the lower rear octant of the wearer's head.
Some past helmet designs employed inflatable pads that extended over the crown or upper front octant of the skull and also over the lower rear octant of the skull. However, such past designs were not inflatable through a single valve as in the present invention. For example, Morgan U.S. Pat. No. 3,609,764 describes a helmet having a number of inflatable cells for sizing, some of which appear to extend over the lower rear octant. However, there is no teaching in the Morgan patent that the cells should or could be interconnected for inflation through a single valve. Similarly, Dunning U.S. Pat. No. 3,761,959 describes an inflatable helmet pad with interconnected front, side and rear members and a separately inflatable top member. Likewise, Schulz U.S. Pat. No. 4,287,613 describes an inflatable helmet pad having a crown compartment and a lower rear compartment, but does not suggest that the crown and lower rear compartments are inflated through a single valve. Achieving uniform inflation of the bladder compartments would be more difficult in designs employing multiple valves, and sizing the helmet to the wearer's head would also be less convenient using multiple valves.
The present invention is directed to overcoming these and other difficulties inherent in prior art helmet designs. In the present invention, an inflatable bladder is mounted on the interior surface of the outer shell of the helmet. The bladder has cells that are inflatable through a single valve and that extend to the lower rear octants of the wearer's head and also to either the crown or the upper front octants of the wearer's head. In use, air is pumped into the bladder to properly position the helmet around the wearer's head. The helmet is held in place primarily by pressure applied by the bladder at the lower rear octants of the wearer's head. The helmet is elevated from the head by pressure applied by the bladder at the upper octants of the wearer's head. In the preferred embodiment, the helmet is fully lined with resilient material interposed between the bladder and the wearer's head.